87 lines
3.8 KiB
Python
87 lines
3.8 KiB
Python
import time
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from platypush.backend import Backend
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from platypush.message.event.sensor import SensorDataChangeEvent, \
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SensorDataAboveThresholdEvent, SensorDataBelowThresholdEvent
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class SensorBackend(Backend):
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"""
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Abstract backend for polling sensors.
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Triggers:
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* :class:`platypush.message.event.sensor.SensorDataChangeEvent` if the measurements of a sensor have changed
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* :class:`platypush.message.event.sensor.SensorDataAboveThresholdEvent` if the measurements of a sensor have gone above a configured threshold
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* :class:`platypush.message.event.sensor.SensorDataBelowThresholdEvent` if the measurements of a sensor have gone below a configured threshold
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"""
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def __init__(self, thresholds=None, poll_seconds=None, *args, **kwargs):
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"""
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:param thresholds: Thresholds can be either a scalar value or a dictionary (e.g. ``{"temperature": 20.0}``). Sensor threshold events will be fired when measurements get above or below these values. Set it as a scalar if your get_measurement() code returns a scalar, as a dictionary if it returns a dictionary of values.
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For instance, if your sensor code returns both humidity and
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temperature in a format like ``{'humidity':60.0, 'temperature': 25.0}``,
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you'll want to set up a threshold on temperature with a syntax like
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``{'temperature':20.0}`` to trigger events when the temperature goes
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above/below 20 degrees.
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:param poll_seconds: If set, the thread will wait for the specificed number of seconds between a read and the next one.
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:type poll_seconds: float
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"""
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super().__init__(**kwargs)
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self.data = None
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self.thresholds = thresholds
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self.poll_seconds = poll_seconds
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def get_measurement(self):
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""" To be implemented in the derived classes """
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raise NotImplementedError('To be implemented in a derived class')
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def run(self):
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super().run()
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self.logger.info('Initialized {} sensor backend'.format(self.__class__.__name__))
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while not self.should_stop():
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new_data = self.get_measurement()
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if self.data is None or self.data != new_data:
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self.bus.post(SensorDataChangeEvent(data=new_data))
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data_below_threshold = {}
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data_above_threshold = {}
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if self.thresholds:
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if isinstance(self.thresholds, dict) and isinstance(new_data, dict):
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for (measure, threshold) in self.thresholds.items():
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if measure not in new_data:
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continue
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if new_data[measure] > threshold and (self.data is None or (
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measure in self.data and self.data[measure] <= threshold)):
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data_above_threshold[measure] = new_data[measure]
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elif new_data[measure] < threshold and (self.data is None or (
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measure in self.data and self.data[measure] >= threshold)):
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data_below_threshold[measure] = new_data[measure]
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else:
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if new_data > threshold and (self.data is None or self.data <= threshold):
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data_above_threshold = new_data
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elif new_data < threshold and (self.data is None or self.data >= threshold):
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data_below_threshold = new_data
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if data_below_threshold:
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self.bus.post(SensorDataBelowThresholdEvent(data=data_below_threshold))
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if data_above_threshold:
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self.bus.post(SensorDataAboveThresholdEvent(data=data_above_threshold))
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self.data = new_data
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if self.poll_seconds:
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time.sleep(self.poll_seconds)
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# vim:sw=4:ts=4:et:
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